Synthesis and metal-support interaction of subnanometer copper-palladium bimetallic oxide clusters for catalytic oxidation of carbon monoxide

摘要

Subnanometer oxide clusters with distinct metal-support interactions have attracted great interest due to their possible superiority in catalytic performance compared to that of conventional metal-oxide nanoparticles. In this paper, we report the solution-based chemical synthesis of a new type of copper- palladium bimetallic oxide clusters anchored to the surface of ceria nanorods. Revealed by aberrationcorrected high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and X-ray absorption fine structure (XAFS) techniques, we have identified that both copper and palladium species are fully oxidized with dominant metal-support interaction contributions by a strongly bound M-Ox-Ce (M = Cu or Pd) structure. However, no direct bond between copper oxide and palladium oxide clusters, i.e. Cu-Ox-Pd, has been verified by experimental evidences, and thus no synergistic effect on the catalytic activity of bimetallic copper-palladium oxide clusters, compared to that of single metal (palladium) oxide clusters, has been demonstrated for the CO oxidation reaction.